RosettaCodeData/Task/Runtime-evaluation-In-an-environment/BBC-BASIC/runtime-evaluation-in-an-environment.basic

      expression$ = "x^2 - 7"
      one = FN_eval_with_x(expression$, 1.2)
      two = FN_eval_with_x(expression$, 3.4)
      PRINT two - one
      END

      DEF FN_eval_with_x(expr$, x)
      = EVAL(expr$)